Car-retarder system for railroads



June 24, 1939. c w. PRESCOTT 319755539 cm RETARDER SYSTEM FOR RAILROADSFiled Dec. 14, 1.927 3 Sheecs-Sheet 1 FIGJ.

J1me 1930. c. w. PREsccTT CAR RETARDER SYSTEM FOR RAILROADS Filed Dec.14, 1927 3 Sheets-Sheet 2 June 24, 1930. c w PRESCQTT 1,766,539

CAR RET'ARDER SYSTEM FOR RAILROADS Filed Dec. 14, 1927 5 Sheets-Sheet 3FIG. 5.

{w ATTORNEY Patented June 24, 1930 UNITED STATES PATENT OFFICE CHARLIE-SW.,PRESCOTT, 0F MILL HILL, ENGLAND, ASSIGNOB '10 GENERAL RAILWAY SIGNALCOMPANY, 01 ROCHESTER, NEW YORK CAB-RETABDER SYSTEM FOR RAILBOADSApplication filed December 14, 1927. Serial No. 289,949.

This invention relates to car retarders of the, track brake type used inclassification or hump yards of railroads, and more particularly tomeans for automatically controlling the braking action of such retardersin accordance with the speed at which the cars to be retarded aremoving.

Although the present invention may be applied'to retarders of variousconstruction and to retarders either located on the main lead where thecars are accelerated, to retarders located on the main classificationyard or switch portion of the classification yard, or may be applied toretarders located on the ladder tracks from which diverge a plurality ofclassification tracks, the invention has been shown applied to retardersin which the passing car wheels are engaged by adjustable brake shoes,and also the invention has only been shown applied to a retarder locatedon the ladder track from which numerous classification tracks diverge.In accordance with the present invention it is proposed to vary thedegree of braking efiected by a particular retarder in accordance withthe speed at which the car is approaching such retarder or passingthrough the same, the speed of the car being preferably determined bythe time required for a car to travel a redetermined distance, that is,by the timeistance interval principle.

Other objects, of the present invention reside in the provision of means'for automatically determining the degree of pressure to be exerted uponthe brake shoe acting on a particular car depending on the weight ofsuch car.

Other objects, purposes and characteristic features of the presentinvention will appear from the description thereof, when considered inconnection with the accompanying drawings.

In describing the invention in detail, reference may be made totheaccompanying drawings in which V Fig. 1 is a layout view of a laddertrack with a plurality of classification tracks branching therefrbmhaving an automatically controlled car retarder embodying the presentinvention applied thereto, of which the various mechanisms have beenshown conventionally Fig. 2 shows on an enlarged scale and in detail oneof the five control treadles shown in Fig. 1 of the drawings;

Fig. 3 shows a modihed'form of treadle and associated mechanism moreparticularly applicable to a railway system where some of the cars to beclassified have four wheel trucks and others have six wheel trucks,which ii. used in the circuit combination shown in Fig. 1 constitutesautomatic retarding mechanism in which the degree of braking of each ofa plurality of cars coupled together is determined by the speed of suchcars; .7

Fig. 4 shows how a large number of treadles such as shown in Fig. 3 maybe connected in the system shown in Fig. 1 so as to have differenttreadles act upon the same time controlled mechanism; and,

Fig. 5 shows the apparatus and circuits contained within the mechanismcasing CRM shown in Fig. 1.

In a car classification system the cars of numerous long freight trainsare detached one or a few at a time, are accelerated in any suitablemanner as by running them off of a hill or hump, which cars are thenswitched into the proper track after which they are retarded by suitablemeans so as to avoid detrimental impact with cars already standing onsuch track. In this connection reference may be had to my prior PatentNo. 1,681,131 granted August 14, 1928, in which Fig. 1 shows such aclassification system in a general way. It is however desired to beunderstood that classification systems may take many various forms, theone to which reference has been made being merely a typical illustrationof such a system, and that the cars may be accelerated by other meansthan the hump shown in this prior application. If cars have beenclassified in this-away new freight trains may be made up by the variouscars which have reached the same destination, namely the sameclassification track.

In order to illustrate how the present invention may be applied, theinvention has been shown, applied to a car retarder system of the trackbrake type, such as shown in the rior application to Howe Ser. No.70,599 led November 21, 1925. This car retarder comprises shoe beams 33dis osed on opposite sides of the rail 1 of a railway track, theparticular railway track illus trated being a ladder track from whichdiverge the classification tracks 2, 3 and 4. These shoe beams 33 are attimes, through the medium of springs,yieldingly urged toward the trackrails by suitable car retarder mechanism contained in the casing CRM,the degree of pressure exerted by the shoe beams 33 depending upon whichone of the live control wires leading to the contacts L", L, L L or L ofthe lever L, or leading to the control relays R", R, R R or R, isenergized. The energization of any one of these wires, except the ofiwire VV will cause the shoe beam 33 to apply pressure to the car Wheelsthrough the medium of the car retarder mechanism as determined by theposition of this car retarder mechanism, and the particular circuit soenergized will, after the mechanism has been moved to the correspondingposition, be opened in the car retarder mechanism casing (JRM in a man-'ner as clearly described in the prior application to Howe. It should benoted that a selecting lever SL has been provided for connecting thefive control wires of the car retarder mechanism to either the handoperated lever L or to the automatic-control mechanism including therelays R, R, R, R and R. This lever SL has been shown in the normalautomatic position, that is, with the lever SL in the position shown thecar retarder is controlled automatically. If this lever SL is moved tothe dotted position the car retarder mechanism CRM may be controlled bythe manuall operable lever L, which lever is preferab y housed in asuitable tower so located that the car retarder is clearly visible.

The control relays R", R, R, R, and R, each contain an upper highresistance winding 5 and a bottom low resistance winding 6. It readilyappears that if the upper winding of any one particular relay isenergized for any reason its armature 7 will be attracted so as toconnect the positive terminal B of a suitable source of energy to thecar retarder mechanism CRM through the winding 6 and by reason of theflow of current in this latter circuit the armature 7 will be maintainedclosed in spite of the removal of ener from the upper winding 5.

Referring to ig. 5 which shows the complete wiring arrangement for aretarder and its control mechanism CRM embodying the present invention,the motor 90, which if rotated in one direction increases the brakingaction of the brake shoes 33 and if rotated in the reverse directiondecreases this braking action, is preferably one of the compound woundtype, havin a shunt field winding 210 and a series fie d w1nd1ng 211,the latter being connected in series with a brake magnet windin 212, thearmature 216 and the commutating field winding 213 of the motor. Asindicated, the shunt winding 210 is always energized, whereas the serieswinding 211 and the commutating winding 213 are energized only while themotor armature is energized either because current is applied thereto orbecause of current flow due to regenerative braking. The brake magnetcoil 212 acts magnetically on the brake 214 to release the brake whilecurrent is being applied to the motor. For the purpose of controllingthe motor by the manually operable lever L or the automaticallycontrolled stick relays R, R, R, R and R", the automatic cutout circuitcontrolleis comprising the cams C", C, C, C and C", operating contacts142, 142, 142, 142 and 142, cooperating with stationary contacts 138-139", 138139, 138 -139, 138 -439 and 138--139, are provided. Thesecutout circuit controllers also serve to drop out the stick relays R, R,R, R and R. Further, the double throw electromagneticall operatedcontactors R and F and a relay ii are required for reasons ap arent fromthe drawings. These cams C, 8 C, C and C will rotate in the direction ofthe arrows shown thereon as the braking of the car retarder isincreased. The forward operating contactor F is in its abnormal activeposition when the retarde is .o be moved to a closed or increasedbraking position, and the reverse contactor R is energized to itsabnormal position when the car retarder is to be moved toward the openor reduced braking position. The forward contactor F is operated to itsabnormal osition as represented by the dotted lines 1f the coil F isenergized, at which time the contact 217 is opened and the contacts 218and 219 are c osed, whereas if the coil R is energized, contactor R isoperated to its abnormal dotted position and the contact 220 is opened,and the contacts 221 and 222 are closed. The magnet windings R and F 2are connected in multiple and directl across the armature of the motor90, and t e energization of these coils aids the springs 223 or 224 inreturning the particular contactor to its normal position after thewinding R or F as the case may be, is again deenergized, after havingbeen energized. In other words, while either the contactor R or thecontactor F is moved to its abnormal dotted position, its correspondingcoil R or F is not energized and therefore the magnetic attraction dueto energization of R or F need only be sufiicient to operate thecontacts in opposition to the force of the springs 223 or 224; whreasupon the deenergization of sire one or the other of the coils R or Fafter having been energized causes the springs 224 or 223, together withthe magnetic force due to the energization of the coils R or F to returnthe contactor to its normal position.

In other words, the armature 216 of the motor 90 is presumably notenergized at the time the retarder is to have its adjusted positionchanged, so that the coils R and F are both dead, so to speak, when oneor the other of coils R and F are energized and the energization of coilR or F need only overcome the force of its corresponding spring 224 or223. On the other hand, the application of current to the motor 90causes a counter electro-motive force to be generated therein whichapplies current to coils R and F so that the deenergization of the coilR or F whichever was energized at the time, causes both the energizedcoil It or F together with its corresponding spring 224 or 223 to returnthe contacts to normal, thus causing a very quick break of the circuit,blowout coils being preferably used to aid in disrupting the are uponopening of these contacts.

In order to permit the operator to accelerate the motor or increase itstorque he may shunt certain resistance units connected in seriestherewith, the arrangement being such however that these resistanceunits can not be shunted until an interval of time after current hasbeen applied to the motor through such resistance units. In other words,current is applied to the motor in two steps, the time spacing betweenthese steps bein controllable by the operator or if dethese resistanceunits need not be shunted at all. In the particular construction shown,the relay H is used for this purpose, and this relay may be energized toshunt such resistance units if both the push button 152 is depressed andone or the other of the contactors R or F is in its active position. Inother words, if a particular stick control relay is picked up the carretarder will be operated to a position corresponding to the relay whichwas operated and if this car retarder has reached such position thecontrol circuit is opened within the mechanism casing CHM and the stickrelay is again dro ped.

It shou d be noted that a selecting relay SR has been provided. Thisselecting relay SR is one of the mechanical stick type and comprisescoils and 11 containing armatures 12 and 13 therein, respectii'ely,these armatures being connected by non-magnetic insulating material asshown, which insulating material carries contacts 14 and 15. From thisconstruction it readily appears that the energization of one or theother of the windings 10 and 11 will, if the relay is not already inthat position, cause the armatures 12 and-13 to be shifted toward theenergized winding, and that the armatures 12 and 13 and the contacts 14and 15 will remain in such position until the other of the coils isenergized. In this connection it should be noted that when the selectingrelay SR is in its normal position the wires W, W and W are allconnected to the wire X and that with the selecting relay SR in its lefthand abnormal position the wire W is connected to the wire X and thewire W is connected to the wire X.

This selecting relay SR is used to limit the pressure which the brakebeams 33 may exert against the wheels of a moving car; the wires X and Xif disconnected, as they will be when the relay SR is operated as theresult of a light car having entered the retarder, will not permit thecar retarder mechanism CRM to be operated to either the third or fourthposition, it being understood that wire X? corresponds to the wireconnected to contact L and wire X corresponds to wire 232 of Fig. 19 ofthe above referred to Howe application. This selecting relay SR isautomatically controlled by weighing mechanism W'M which may take anysuitable form. For instance, in practice this weighing mechanism WM maybe a weigh bridge or scale for indicating the Weight of the car andwhich will have contacts associated therewith which are closed duringthe passage of a car providing such car weighs more than a predeterminedamount. Also, this weighing mechanism WM may comprise a rail deflectioncontact which closes a circuit in response to deflection of the rail orrails so long as a car exceeding a predetermined weight passes over suchrails. This weighing mechanism WM has .been shown conventionallv, and inthis conventional showing a movable contact 20 is held in. its normalposition by spring 21, this spring 21 and contact 20 being so associatedwith the rail of the railway track that the contact 20 bridges thestationary contacts 22 and closes a circuit beginning at one terminal Band ending at another terminal C of a suitable battery including thecoil 10 of the selector relay SR if a heavy car passes over such rails.In other words, the coil 10 of the selector relay SR is energized it acar weighing more than a certain amount passes by the location of theweighing mechanism IVM. When the car in question has passed entirelythrough the car rctarder it engages a trcadle which treadlc through themedium of contact 23 momentarily energizes the coil 11 of the selectingrelay SR and thereby returns the selecting relay SE- to its normalposition.

In order to determine the speed of a car approaching or passing throughthe car retarder several time element relays T3 and Tilt and TR havebeen provided. Each of these time element relays includes a coil 24having a movable armature or core therein fastened to, but insulatedfrom, a movable contact 26, which contact is adapted to engagingstationary contacts K", K, K K, and la. The movable contact 26 is freeto move upward very quickly upon energization of the coil 24, but ifthis coil 24 is deenergized the movable contact 26 will very raduallygravitate to a lower position. his gradual return of the contact 26 isdue to the retarding effect of the dash pot 27, having a valve t pepiston 28 therein, and although this va ve type piston 28 permits freeupward movement, downward movement of the iston 28 is retarded by therestricted openlng 29 in the dash pot 27.

In the particular form of the invention illustrated there are providedtreadles T, T, T, and T having contacts 41, 42, 43, and 44 associatedtherewith, which contacts are preferably closed during the passage ofthe first wheel of the car running on that rail but not during thepassage of the second, third and fourth wheel of such car. One form ofmechanism for accomplishing this desired function is shown in Fig. 2 ofthe drawings.

Referring to Fig. 2, the treadle T in the conventional form shownconsists of a vertically disposed plunger extending through a holecontained in the rail 1 of the railway track, which plunger T ispivotally fastened to the arm 30, which arm 30 is pivoted on a pin 31and has a spring dog 32 connected to the end thereof. This dog 32cooperates with a ratchet wheel 34 having the same number of teeththerein as the number of wheels on one side of a car, which in theparticular arrangement shown is four because the freight car F which isintended to represent freight cars of the usual construction, have onlyfour wheels on each side thereof. The parts are so proportioned that thepassage of a car over the treadle T wil cause the ratchet wheel 34 to bemoved through an angle of 90 and if this treadle T is released thespring 36 will return the treadle T as well as the dog 32 back to itsnormal position so that the passage of the second wheel of the car overthis treadle T will cause another 90 rotation of the ratchet wheel 34.The ratchet wheel 34 is fastened to the rotatably supported shaft 37 bysuitable means, such as a key, and to this shaft is secured a cam 38which through the medium of the roller will depress the contact 41against the tension of the spring 42 during the passage of the firstwheel of the car, but will not cause such depression of the contact 41during the passage of the second, third and fourth wheel of the car. Inother words the treadles T T etc. are of such construction that theircorresponding contacts are operated once for every four wheels whichdepress the treadle thereof.

Operation In order to get a clear understanding of the operatingcharacteristics of the system illustrating an embodiment of the presentinvention, let us consider the passage of a car along the track rails 1and through the car retarder conventionally shown. Let us assume thatthe car F has been accelerated by suitable means not shown in thedrawings in the direction of the arrow and that this car F is so lightthat it will not cause closure of the contacts 20-22. When the firstwheel of the car F passes over the treadle T it causes closure of thecontacts 4145, thereb energizin the coil 24 of the timing relay R throngi a circuit leadin from the terminal B of a suitable source 0 energy,through the contacts 41-45, wire 46, winding 24 of the timing relay TR,to the common return wire C connected to the other terminal of saidsource of energy. The closure of this circuit causes the timing relay TRto quickly move its movable core and in turn contact 26, to the extremeupper dotted position in engagement with the stop and in contact withthe stationary contact K. As the next three wheels of the car pass overthe treadle T the contacts 4l-4 are not closed because there is merelyidle movement of the ratchet wheel 34 (see Fig. during these threedepressions of the treadle T. Let us assume that the car F is moving atsuch a high rate of speed that the movable contact 26 of the timingrelay TB is still in engagement of the stationary contact K when thefirst wheel of the car F strikes the second treadle namely the treadle TAs the first wheel of this car F depresses the treadle T the contacts42-47 will momentarily close, thereby energizin the coil 24 of thetiming relay TR throug the following circuit 2- beginning at theterminal B of a source of ener y, contacts 42-47, wires 49 and 50, wining 24 of the timing relay TR to the common return wire C connected tothe other side of said source. This momentary energization of thiswinding causes the movable contact 26 of the timing relay TR to assumethe extreme upper dotted position. Also this momentary closure ofcontacts 42-47 causes energization of the high resistance winding 5 ofthe stick relay B, it being remembered that the speed of the car F wasso high that the contact 26 of the timing relay TR would not allow sufiicient time for this contact to leave the stationary contact K by thetime the first wheel of the car reached the treadle T; it should also beremembered that the car in uestion is so light that its passage over theweighin machine WM did not cans? o eration o the selecting relay SR.This circuit for the high resistance winding 5 of the stick relay B maybe traced as follows :beginni ng at terminal B, contact til-e7, wires 49and 51, contact 26 of the timing relay Til contact li oi this sametiming relay TR, wire Z the high resistance winding 5 of the stick relayit", wire W, contact 14 of the selecting relay SR, wire X through themechanism GEM of the car retarder more specifically disclosed in theapplication of Howe heretofore mentioned, to the common return wire Cconnected to the other side of said source of energy. The completion ofthis circuit causes the armature '2 of the stick relay to be attractedthereby closing a series stick circuit for operating the car retardingmechanism and maintaining the relay R' energized, which may be traced asfollows :--beginning at the terminal B. contact 'Z of the stick relay Fithe low resistance winding 6 of this relay, wire W contact- 14, wire Xcontact n2 contact 139 wire 24:5, contactor E to the common return wireC. The closure of this low resistance stick circuit applies sufficientcurrent to the car retarder mechanism to cause the mecha nism to beoperated from the 05 position, or zero position, to the position 2 towhich the retarder is moved upon energizing wire X in which positionsufiicient braking will he efiected for light cars it being understoodthat a light car should. not be retarded as effectively as a heavy carreason of the tendency of the car wheels to rise up be tween the brakeshoes of the retarder if the braking pressure exerted by these brakeshoes is excessive. It should be noted that if in the meantime thecontact 26 of the tining relay 'lR has moved ofi of the stationarcontact K this will not in any way ailect the condition of the stickrelay it", because this stick relay is energized through the stickcircuit including the low resistance winding 6 assuming that thearmature or contact 7 of this relay is still attracted. As soon as thecar retarder mechanism has oper ated the car retarder to the secondbraking position the stick circuit for the relay R is broken at thecontact 142 (see l i 5) within the mechanism casing Gilli/l an the relayR is ale-energized, for reasons heretofore explained.

in exactl the same man oi the car rom the tread T will cause one of theR", or R to be energized distance of movement I" the contact 26 of thetiming relay Til? during the time interval required for the car to movefrom the treadle T to the treadle T In other words, if the car in movingfrom the treadle T? to the treadle T had consumed so much time that thecontact 26 of the timing relay TR would have been permitted to move allthe way back to its normal position in contact with the stationarycontact K", the sticlr relay would have been picked up and through itsstick circuit including the wire W" and the contact 142 (see Fl 5) wouldhave operated the car retarder RM to the 0d or zero position. in thesame manner as just described the timing relays TR, TR and T3 areenergized to control the retarder depending on the speed of the car whenmoving from one treadle to the next succeeding treadle.

Let us now assume that a heavy car is moving from left to right and thatits passage over the weighing mechanism WM causes closure of thecontacts 2022. The closure of these contacts 2022 completes the circuitfor energizing the coil 10 of the selecting relay SR, which circuit mayreadily be traced in the drawings. The completion of this latter circuitcauses the selecting relay SE to shift its contacts 14: and 15 to theleft so as to connect the wire W with the wire X and connect the wire Vf to the wire X When the first wheel of the heavy car strikes thetreadle T it closes an energizing circuit for the coil 24 of the timingrelay TR thereby causing the contact 26 thereof to be moved to thedotted position. The passage of the next three wheels of this car willnot effect closure of the contacts 4il45 for reasons heretofore given.

Let us assume that the contact 26 has moved to engage the stationarycontact K during the time that this heavy car moved from the treadle Tto the treadle 'l. It will be noted that the closure of contacts 42%?upon the arrival of the car at trcadle T applies energy to the stickrelay R throu h the following circuit B, contacts 12.2%? wires El-51,contact 26 of the timing relay 'llit stationary contact K wire Z highresistance winding 5 of the stick relay R wire V7 contact 15 (which hasnow been shifted to the left) wire K through the contact 142 which nowassumes its right hand position through the relay F in the car retardermechanism (see Fig. 19 of said Howe application) to the common returnwire C. The resistance of the circuit just traced is so high thatinsufiicient current flows to cause operation of the car retardermechanism CHM and therefore the car retarder brake shoe beams 33 willnot yet be operated. The closure oil this pick-up circuit for the stickrelay E effects closure or the following stick circuit by reason of theattraction of the armature '7 :--beginning the terminal B, contact orarmature 'Z' of the relay R the low resistance windingof this relay wireW contact 15 wire X contact a 142 (see Fig. 5), relay F through themechanism oi the car retarder, to the comlltl IllS

mon return wire C. The completion of this circuit causes the carretarder mechanism to be moved to the third braking position which willeffect a hi her degree of braking than does the secon braking positionto which the car retarder was operated when the light car passedtherethrough, for reasons heretofore explained. It should especiall benoted that even though the heavy car ust considered moved at a lowerspeed from the treadle T to the treadle T than did the light car, thisheavy car was retarded more severely than was the li ht car. The reasonfor the need of this ad itional braking is that the amount ofretardation necessary to retard a car depends lar ely on the weight ofsuch car, because the inetic energy stored in such moving car isdirectly proportional to the weight thereof. In this connection itshould be noted that the car retarder may assume the position zero,position 1 or position 2, when a light car passes therethrough, but mayassume any of the five positions when a heavy car passes therethrou h.In other words, the present invention oes not only automatically fix there tardation in accordance with the speed at which the car to beretarded travels but also fixes the amount of retardation in accordancewith the weight of such car.

Mada d construction-Although freight cars 0 the usual type have fourwheel trucks, that is have two such trucks thus resulting in four wheelson each side of the car, the tendency of car construction is directedtoward six wheel trucks, and in order to apply the present invention toa system where the cars to be classified may have either four or sixwheels on each side thereof an arrangement has been shown in Fig. 3 ofthe drawings whereby the treadle if once depressed will remain depresseduntil the car has moved a full car length after such depression, afterwhich the treadle will be released. In Fig. 3 of the drawings has beenshown a track rail which has treadles T and T etc., associatedtherewith. Each of these treadles is fastened to a sector 60 by suitablemeans, such as a pin 61, which seetor is ivoted about the pin 62. Thissector is held in its normal position against the stop 63 by the spring64. This sector has a contact 65 fastened thereto but insulatedtherefrom which is adapted when moved from its normal to its dottedposition to momentarilv engage the contact 66, but cannot engage thecontact 66 when it is moved from its dotted to its normal position. Thisby reason of the provision of the insulation 67 on one side of thecontact 66, this contact 66 being ivoted on pin 69 and bein held in itsnonna position by spring 68. The sector 60 is not only urged to itsnormal position by the spring 64, but is held in such position by t ebrake shoe 70 held against the circumferential edge of the sector 60 bythe spring 71. This spring 71 is guided by the pin 72 passing throughthe stationary lug 73 and having its other end connected to the core 71I contained in the coil 75. From this construction it readily appearsthat if the treadle T is forced down the sector 60 is moved in spite ofthe brake 70 due to the tremendous force acting on this treadle. Ii nowthe wheel passes off of the treadle T" the spring 64 Wlll not besufficiently strong to return the sector 60 so long as it is engaged bythe brake shoe 70.

In accordance with one form of the present invention the treadles shownin Fig. 3 of the drawings are connected in the circuit arrangement shownin Fig. 1 of the drawings as conventionally shown in Fig. 4 of thedrawings.

Operation 0 the modified constructions- Referring to igs. 3 and 4 andbearing in mind the construction shown in Fig. 1 to which the apparatusshown in Fig. 3 is applied in a manner as indicated in Fig. 4, let usassume that a car is moving from left to right over the track rails 1 inFig. 4 of the drawings, and that it passes over the treadle T which isof a construction as shown in Fig. 3. The passage of the first wheel ofthe car over the treadle T causes it to be depressed and held by thebrake shoe 7 O. During this movement of the treadle T from its normal toits dotted position there is a momentary engagement of the contact 65with the contact 66, during which engagement energy is applied throughwire 46 to the winding 24 of the timing relay TR (see Fig. 4) and isalso applied through the wire 59 to the contact 26 of the timing relayTR. The application of current to the contact 26 of the timing relay TRwill cause the car retarder to be moved to the zero or ofi positionthrough the medium of W for reasons heretofore described in connectionwith Fig. 1 of the drawings if it did not already assume this position.The momentary application of current to the winding of the timin relayTR causes the contact 26 to be li ted to the extreme upper positionagainst the stop (see Fig. 1). Let us assume that the car in questioncontinues its movement from left to right and after an interval of timestrikes the treadle T. Operation of the treadle T by the first car wheelof this car causes energy to be applied to the contact 26 of the timingrelay TB. through wires 49 and 51, the application of which ener willpick up one of the relays R", R R, fi or R depending on the extent thatthe contact 26 of this relay has moved during the time the car hastravelled from the treadle T to the treadle T and in turn will cause thecar retarder to assume the proper braking position in accordance withthe weight and the speed of the car in question; also, the depression ofthe treadle T causes current to be momentarily applied to the coil 75associated with the treadle T parativel messes which energization ofthis coil releases the brake and permits the spring 6% to return thetreadle T to its normal position. During the return of the treadle T tonormal although the contact 66 will be moved no electric circuit iscompleted by reason of the insulated portion 67 heretofore mentioned.Also, the depression of the treadle T by the first car wheel of the carinquestion causes energy to be applied to the wind ing 2 of the timingrelay TR through wires 49 and 50, so that this timing relay maydetermine the speed of the car while moving from the treadle T to thetreadle T In the same we as described in connection with the treadle thepassage of the car over the various other treadles will cause theretarder to assume a braking position tending to bring the car speeddown to a predetermined value and hold it there. In the schematicarrangement shown in Fig. 4: 1t is assumed that the retarder usedextends over the entire distance of the treadles T T either as a singleretarder oras a series of separate retarders. Referring to Fig. 4 itwill be noted that the nine treadles shown T to T inclusive, are soconnected that every third treadle is connected to the same timing relayTR. This construction is a very economical arrangement by reason of thefew timing relays and control relays required for a comlong stretch oftrack over which the spec of the cars is repeatedly checked at recurringspace intervals.

In order to illustrate applicants invention it has for convenience beenshown applied to a ladder track of a car classification slylstemalthough it is equally applicable to t e main lead either on the slopeof the accelerating hump or at the bottom thereof, is applicable whenthe main lead diverges into the ladder tracks and is applicable to theclassification track itself. Also although only one arrangement forbraking a car in accordance with both its weight and its speed has beenshown it should be understood that other arrangements may be used withinthe scope of the present invention; for instance, instead of determiningthe speed of the car by the time-distance interval principle it may bedetermined by a speed responsive device driven by the moving car. Inother words, the particular arrangement shown has been illustrated toshow typical application of the present invention rather than to theexact construction preferably used in practicing the invention or thescope of the same; and it is desired to be understood that variouschanges, modifications and additions may be made to adapt the inventionto the particular classification system and the pan ticular type ofretarder to which the invention is to be ap lied without departing fromthe scope oft e present invention or the idea of means underlying thesame except as demanded by the appended claims.

What I claim is 1. In a combined manual and automatic car retardingsystem, the combination with a car retarder of the type in whichsuitable electrically controlled power operated mechanism is employedfor determining the degree of retardation to be effected, manuallyoperable means for controlling the power operated mechanism of such carretarder, automatic means for controlling the power operated mechanismof such retarder, and selecting means whereby either said manuallyoperable means or said automatic means may be selected and renderedcapable of controlling the power operated mechanism.

2. In a combined manual and automatic car retarding system, thecombination with a car retarder of the type in which suitableelectrically controlled power operated mechanism is employed fordetermining the degree of retardation to be effected, manually operablemeans for controlling the power operated mechanism of such car retarder,automatic means for controlling the power operated mechanism of such carretarder, and manually operable selecting means which if in onecondition permits said power operated mechanism to be controlled by saidmanually operable means and which if in another condition permits saidpower operated mechanism to be controlled by said automatic means.

3. An automatically controlled car retarder of the track brake typecomprising, brake shoes disposed alon the side of the track for engagingthe si es of the wheels of passing cars, power operated means foradjusting the pressure at which said shoes are urged against the wheelsof a passing car, and automatic means for repeatedly checking up the seed of a car as it moves through the retar er and for operating saidpower operated means to adjust the pressure exerted by said brake shoesin accordance with actual speedpf the car at the time.

4. An automatic car retarder .system -for retarding cars in accordancewith their actual eed' comprising, a car retarder or the traih braketype in which brake shoes along the track engage the wheel sides of arailway car, power operated means for adjusting the pressure exerted bysaid brake shoes, treadles along the track for manifesting when a carpasses a particular point, a timing device for each successive pair oftreadles for determining the speed of the car while traveling from onetreadle to the next treadle, and means for controlling said poweroperated means to cause-said brake shoes to be applied to an extentdepending on the speed of the car.

5. An automatic car retarder system according to claim t in which thereare fewer timing devices than there are spaces between successivetreadles.

(3. An automatic car retarder syst cording to claim 4, in which thevari. d: vices are so correlated that each of the timing devices iscapable of determining the speed of a car moving through any one ofseveral different sections of t :l:.

T. An automatically controiled car retarder. of the track brake typecomprising, brake shoes disposed along he side of the track for engagingthe sides 01' the wheels of passing cars, power operated means foradjusting the pressure at which said shoes are urged against the wheelsof a passing car, and automatically controlled means for controllingsaid )ower o crated means in accordance with t e spec atwhich a'car ismoving through said retarder and in accordance with the weight of saidcar.

8. An automatically controlled car retarder of the track brake typecomprising, brake shoes disposed along the side of the track forengaging the side of the wheels of passing cars power operated means foradusting the pressure at which said shoes are urged against the wheelsof a passii car, and automatic means for partly releac i the brakingaction or increasing the braking action of said retarder as a car assesthrough said retarder depending on tie rate of retardation of said car.

9. An automatically controlled car retardei' of the traclr. brake typecomprising, brake shoes disposed along the side of the track for thesides the wheels of passing cars, power operated means for adjusting thepressure at which said shoes are urged against the wheels of a passingcar, and automatic means having its operation dependent upon the speedat which a car is moving through the retarder for increasing ordecreasing the hr "ng action of said rttarder as conditions rec .re toobtain the proper braking action.

10. An automatically controlled car retarder of the track brake typecomprising, brake shoes disposed along the side of the track forengaging the sides of the wheels of passing ears, power operated meansfor adjusting the ressure at which said shoes are urged against thewheels of a passing car, and automatic means or" the time-distanceinterval type functioning in accordance with the speed at which a car ismovin throu h said retarder for controlling said retarder to eitherincrease or decrease the braking action of said retarder depending uponthe speed of said car.

11. An automatically controlled car retarder of the track brake typecomprising, brake shoes disposed along the side of the track forengaging the sides of the wheels of passing cars, power operated meansfor adjusting the pressure at which said shoes are urged againstthewheels or a passing car, and plurality of slow-acting devices each asociated with a diilerent stretch of track and e ch assuming a conditiondepending upon the speed of the car when moving through the associatedstretch of track and each controllin said retarder in accordance withthe speed of said car when passing throw such stretch. of track.

12. An automatically controlled car retardcr of the track brake typecomprising, brake shoes disposed along the side of the track forengaging the sides of the wheels of passing cars, power operated meansfor adjusting the pressure at which said shoes are urged against thewheels of a passing car, and automatically controlled means forcontrolling said power operated means in accordance with the speed atwhich a car is moving while it is being braked by said retarder and alsoin accordance with the weight of said car In testimony whereof T atlixmy si mature.

CHARLES w. PRES ()TT.

